1. Field of Invention
The present invention relates to a fan. More particularly, the present invention relates to a centrifugal fan.
2. Description of Related Art
Conventional fans are commonly divided into two types: axial fans and centrifugal fans. The axial fans intakes air along an axial direction of the impeller and outputs air along the axial direction of the impeller, thereby being referred as “axial fans”. The centrifugal fans intakes air along an axial direction of the impeller and outputs air along a radial direction of the impeller.
Referring to FIG. 1, it illustrates a cross-sectional view of a conventional impeller of the centrifugal fan. The centrifugal fan 100 includes a case 102 housing an impeller 104. The case 102 has air inlets (102a, 102b) located at two opposite sides of the impeller 104 and along an axial direction thereof. When the impeller 104 rotates, airflows are introduced into the case 102 through two air inlets (102a, 102b) and guided along a radial direction of the impeller 104 so as to become pressure-enhanced airflows 105. When the pressure-enhanced airflows 105 accumulate up to a threshold, part of the airflows may leak through the air inlet 102b along a direction 106, thereby decreasing an output airflow pressure of the centrifugal fan 100. Besides, noises are usually incurred due to the lost of pressure-enhanced airflow 10 through the air inlets.
For the crowded-art like the fan design industry, any improvements in performance, e.g. increasing an airflow pressure or reducing noises, need to be constantly perused. There is no exception for the forgoing problems.